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/*
* Digital I/O driver for Technologic Systems I2C FPGA Core
*
* Copyright (C) 2015, 2018 Technologic Systems
* Copyright (C) 2016 Savoir-Faire Linux
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* This program is distributed "as is" WITHOUT ANY WARRANTY of any
* kind, whether expressed or implied; without even the implied warranty
* of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License version 2 for more details.
*/
#include <linux/gpio/driver.h>
#include <linux/i2c.h>
#include <linux/of_device.h>
#include <linux/module.h>
#include <linux/regmap.h>
#define DEFAULT_PIN_NUMBER 32
/*
* Register bits used by the GPIO device
* Some boards, such as TS-7970 do not have a separate input bit
*/
#define TS4900_GPIO_OE 0x01
#define TS4900_GPIO_OUT 0x02
#define TS4900_GPIO_IN 0x04
#define TS7970_GPIO_IN 0x02
struct ts4900_gpio_priv {
struct regmap *regmap;
struct gpio_chip gpio_chip;
unsigned int input_bit;
};
static int ts4900_gpio_get_direction(struct gpio_chip *chip,
unsigned int offset)
{
struct ts4900_gpio_priv *priv = gpiochip_get_data(chip);
unsigned int reg;
regmap_read(priv->regmap, offset, ®);
return !(reg & TS4900_GPIO_OE);
}
static int ts4900_gpio_direction_input(struct gpio_chip *chip,
unsigned int offset)
{
struct ts4900_gpio_priv *priv = gpiochip_get_data(chip);
/* Only clear the OE bit here, requires a RMW. Prevents potential issue
* with OE and data getting to the physical pin at different times.
*/
return regmap_update_bits(priv->regmap, offset, TS4900_GPIO_OE, 0);
}
static int ts4900_gpio_direction_output(struct gpio_chip *chip,
unsigned int offset, int value)
{
struct ts4900_gpio_priv *priv = gpiochip_get_data(chip);
unsigned int reg;
int ret;
/* If changing from an input to an output, we need to first set the
* proper data bit to what is requested and then set OE bit. This
* prevents a glitch that can occur on the IO line
*/
regmap_read(priv->regmap, offset, ®);
if (!(reg & TS4900_GPIO_OE)) {
if (value)
reg = TS4900_GPIO_OUT;
else
reg &= ~TS4900_GPIO_OUT;
regmap_write(priv->regmap, offset, reg);
}
if (value)
ret = regmap_write(priv->regmap, offset, TS4900_GPIO_OE |
TS4900_GPIO_OUT);
else
ret = regmap_write(priv->regmap, offset, TS4900_GPIO_OE);
return ret;
}
static int ts4900_gpio_get(struct gpio_chip *chip, unsigned int offset)
{
struct ts4900_gpio_priv *priv = gpiochip_get_data(chip);
unsigned int reg;
regmap_read(priv->regmap, offset, ®);
return !!(reg & priv->input_bit);
}
static void ts4900_gpio_set(struct gpio_chip *chip, unsigned int offset,
int value)
{
struct ts4900_gpio_priv *priv = gpiochip_get_data(chip);
if (value)
regmap_update_bits(priv->regmap, offset, TS4900_GPIO_OUT,
TS4900_GPIO_OUT);
else
regmap_update_bits(priv->regmap, offset, TS4900_GPIO_OUT, 0);
}
static const struct regmap_config ts4900_regmap_config = {
.reg_bits = 16,
.val_bits = 8,
};
static const struct gpio_chip template_chip = {
.label = "ts4900-gpio",
.owner = THIS_MODULE,
.get_direction = ts4900_gpio_get_direction,
.direction_input = ts4900_gpio_direction_input,
.direction_output = ts4900_gpio_direction_output,
.get = ts4900_gpio_get,
.set = ts4900_gpio_set,
.base = -1,
.can_sleep = true,
};
static const struct of_device_id ts4900_gpio_of_match_table[] = {
{
.compatible = "technologic,ts4900-gpio",
.data = (void *)TS4900_GPIO_IN,
}, {
.compatible = "technologic,ts7970-gpio",
.data = (void *)TS7970_GPIO_IN,
},
{ /* sentinel */ },
};
MODULE_DEVICE_TABLE(of, ts4900_gpio_of_match_table);
static int ts4900_gpio_probe(struct i2c_client *client,
const struct i2c_device_id *id)
{
struct ts4900_gpio_priv *priv;
u32 ngpio;
int ret;
if (of_property_read_u32(client->dev.of_node, "ngpios", &ngpio))
ngpio = DEFAULT_PIN_NUMBER;
priv = devm_kzalloc(&client->dev, sizeof(*priv), GFP_KERNEL);
if (!priv)
return -ENOMEM;
priv->gpio_chip = template_chip;
priv->gpio_chip.label = "ts4900-gpio";
priv->gpio_chip.ngpio = ngpio;
priv->gpio_chip.parent = &client->dev;
priv->input_bit = (uintptr_t)of_device_get_match_data(&client->dev);
priv->regmap = devm_regmap_init_i2c(client, &ts4900_regmap_config);
if (IS_ERR(priv->regmap)) {
ret = PTR_ERR(priv->regmap);
dev_err(&client->dev, "Failed to allocate register map: %d\n",
ret);
return ret;
}
ret = devm_gpiochip_add_data(&client->dev, &priv->gpio_chip, priv);
if (ret < 0) {
dev_err(&client->dev, "Unable to register gpiochip\n");
return ret;
}
i2c_set_clientdata(client, priv);
return 0;
}
static const struct i2c_device_id ts4900_gpio_id_table[] = {
{ "ts4900-gpio", },
{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(i2c, ts4900_gpio_id_table);
static struct i2c_driver ts4900_gpio_driver = {
.driver = {
.name = "ts4900-gpio",
.of_match_table = ts4900_gpio_of_match_table,
},
.probe = ts4900_gpio_probe,
.id_table = ts4900_gpio_id_table,
};
module_i2c_driver(ts4900_gpio_driver);
MODULE_AUTHOR("Technologic Systems");
MODULE_DESCRIPTION("GPIO interface for Technologic Systems I2C-FPGA core");
MODULE_LICENSE("GPL");
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